Nb-Ta-Ti oxides fractionation in rare-metal granites: Krasno-Horni Slavkov ore district, Czech Republic

作者：Rene Milos^*; Skoda Radek

来源：Mineralogy and Petrology, 2011, 103(1-4): 37-48.

DOI：10.1007/s00710-011-0152-z

Nb-Ta-Ti-bearing oxide minerals (Nb-Ta-bearing rutile, columbite-group minerals) represent the most common Nb-Ta host in topaz-albite granites and related rocks from the Krasno-Horni Slavkov ore district. Tungsten-bearing columbite-(Fe), W-bearing ixiolite, wodginite and tapiolite-(Fe) are extremely rare in these rocks. Rutile contains significant levels of Ta (up to 37 wt.% Ta(2)O(5)) and Nb (up to 24 wt.% Nb(2)O(5)), with Ta/(Ta + Nb) ratio ranging from 0.04 to 0.61. Columbite-group minerals are represented mostly by columbite-(Fe) and rarely by columbite-(Mn), with Mn/(Mn + Fe) ratio ranging from 0.23 to 0.94. The exceptionally rare Fe-rich, W-bearing ixiolite occurs only as inclusions in Nb-Ta-bearing rutile from quartz-free alkali-feldspar syenites (VysokA1/2 Kamen stock). Wodginite was found only in the topaz-albite microgranite of gneissic breccia matrix that occurs in the upper most part of the Hub topaz-albite granite stock. In wodginite, the Mn/(Mn + Fe) ratio is 0.42-0.51, whereas the coexisting tapiolite-(Fe) has a distinctly lower Mn/(Mn + Fe) ratio close to 0.06.

• 出版日期2011-11